60
Late submissions
PIX03
PIX04
THE INVOLVEMENT OF TWO PLASTIDIAL ARABIDOPSIS THALIANA
ABC1 KINASES IN IRON DISTRIBUTION AND OXIDATIVE STRESS
RESPONSE.
MANARA A., DALCORSO G. AND FURINI A.
Dipartimento di Biotecnologie, Università degli Studi di Verona, Strada le Grazie 15, 37134 Verona.
Keywords: Abc1 kinases, chloroplast, iron, oxidative stress.
The Abc1 protein kinases are a large family of proteins involved in respiration in bacteria and mitochondria, even though, knowledge about their putative functions in chloroplasts is still limited. We carried out a functional characterization of AtSIA1, a chloroplast
Arabidopsis thaliana Abc1-like protein, focusing on its potential redundancy with its
homolog AtOSA1: A. thaliana knock-out mutant lines for AtSIA1 and AtOSA1 were considered and the double mutant was created. A reduction in content of plastidial iron and in the abundance of components of the Cytb6f complex were observed in mutants,
suggesting that both AtSIA1 and AtOSA1 affect iron distribution within the chloroplast. Moreover, mutant plants accumulate more ferritin and superoxide than wild type plants, and their enhanced sensitivity to oxidative stress was supported by the upregulation of the antioxidant networks. Mutants produce altered levels of prenylquinones, but only atsia1 plants develop larger plastoglobules, containing higher levels of VTE1. Taken together, these data suggest that AtSIA1 and AtOSA1 may act as protein kinases in signaling pathways that influence plastidial responses to oxidative stress.
DIVERSE CIS-REGULATION OF A VACUOLAR METAL TRANSPORTER
IN ARABIDOPSIS THALIANA AND ARABIDOPSIS HALLERI.
FASANI E.1, DALCORSO G.1, VAROTTO C.2, LI M.2 AND FURINI A.1
1 Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona. 2 EcoGenomics Group, Edmund Mach Foundation, Via Mach 1, 38010 San Michele all'Adige
(TN).
Keywords: metal hyperaccumulation, VMT, expression, promoter, GUS.
The vacuolar metal transporter VMT is involved in metal hyperaccumulation. VMT is expressed at higher levels in metal hyperaccumulators Arabidopsis halleri and Noccaea
caerulescens than in non-accumulator species, such as Arabidopsis thaliana. To gather
information about the different transcriptional cis-regulation of VMT, we performed an in
silico comparison of promoter sequences amplified from a variety of Brassicaceae species,
including both hyper- and non-accumulators, and three putative motifs were identified and chosen for further in vivo analysis. Three different sequences corresponding to the VMT promoter were amplified in A. halleri. Truncated forms were generated isolating the core sequence and deleting two of the motifs, while site-directed mutagenesis was performed on the third motif. The cloned sequences were fused to the GUS reporter gene and the obtained constructs were used for A. thaliana transformation (AtVMT promoter was used as control). Promoters of both A. thaliana and A. halleri VMT are active in roots, guard cells and hydathodes, but only Ah-pVMT seems to be specific for leaf mesophyll and trichomes.
